Unconventionally Designed Tracking Loop Adaptable to Plasma Sheath Channel for Hypersonic Vehicles

Area of Science:

• Aerospace Engineering
• Signal Processing
• Plasma Physics

Background:

• Hypersonic vehicles generate plasma sheaths during atmospheric reentry.
• Plasma sheaths cause significant signal amplitude attenuation and phase fluctuations.
• Traditional phase-locked loops (PLLs) are unreliable under these conditions.

Purpose of the Study:

• To analyze the impact of plasma sheath-induced amplitude attenuation on traditional PLLs.
• To propose a robust signal tracking loop for hypersonic communication.
• To ensure reliable carrier tracking despite severe channel variations.

Main Methods:

• Comprehensive analysis of amplitude attenuation effects on traditional PLLs.
• Development of an unconventional Kalman filter (KF) tracking loop.
• Modeling time-varying amplitude attenuation using an autoregressive model.
• Incorporating statistical characteristics of amplitude and phase fluctuations into KF equations.

Main Results:

• Traditional PLLs fail in severe time-varying amplitude attenuation environments.
• The proposed KF-based tracking loop demonstrates stability.
• Reliable signal carrier tracking is achieved even at low signal-to-noise ratios (-10 dB) in the Ka band.

Conclusions:

• The proposed KF tracking loop overcomes limitations of traditional PLLs for hypersonic communication.
• This method effectively mitigates signal degradation caused by plasma sheath effects.
• The KF-based approach ensures robust signal reception in extreme flight conditions.